Question 24/XI - Enhancement and extension of the Q.500, Q.544-Series of Recommendations on digital exchanges Considering (a) that the Q.500-Series of Recommendations on digital exchanges have been developed over the last three CCITT study periods; (b) that a large number of digital exchanges complying with these Recommendations have already been supplied to administrations and RPOAs; (c) that operational experience in an IDN environment of digital exchanges complying with these Recommendations is rapidly building up; (d) that there is a trend in exchange design towards the separation and centralization of the intelligence required to support new and enhanced features, from that required to support basic circuit switching; and further considering: (e) that many national and international IDNs are already being evolved to become ISDNs; (f) that there is a need to develop these Recommendations in respect of aspects arising from: -the impact on digital exchanges of the evolution of the telecommunications management network (TMN), -the impact on exchange performance design objectives, OAM objectives and measurements of packet mode services, supplementary services etc., -the impact on exchange overload characteristics due to, common channel signalling traffic, data information transfer between exchanges and remote operations centressystems, etc.; (g) that there is a need to develop these Recommendations in respect of aspects arising from the requirement for digital exchanges to operate in conjunction with both public land mobile networks and competing fixed land networks; (h) that new services including broadband and data will be introduced in ISDNs and may require special interface and other functions within digital exchanges; (i) that digital transmission technology will continue to evolve, possibly at a different rate from exchanges and the latter may be required to support more than one such technology, e.g., the use of lower bandwidth transmission systems in rural areas which may require changes in the design of small digital exchanges; (j) that connections other than bi-directional circuit switched connections may be required to meet future service requirements, What additions and modifications should be made to the existing Q.500-Q.544-Series of Recommendations on digital exchanges? Note - This Question should be studied in liaison with Study Group II. ANNEX (to Question 24/XI) Proposed 3.5.4.2.2 of Recommendation Q.512; CV1 channel structure This annex contains a proposal for a 3.5.4.2.2 of Recommendation Q.512 which is now currently marked as for further study. "3.5.4.2.2 CV1 channel structure The frame structure in the CV1 channel is given in Figure 5Q.512 containing: -Abits words A1..A4 for the control of the activation deactivation of the line and T interface, the set up of loops and the signalling of fault conditions. -Mbits octets for the transfer of the monitoring channel data. -Ebit to indicate the validity of the following Mbit. -Tbit for the transmission of transparent data to be conveyed across the line. The use of the T bit is for further study. -Rbits representing a multiframe alignment word." Channel time slot no. of frames 0 1 2 3 4 5 6 - + - + SYN B1,1 B2,1 B1,2 B2,2 D+C B1,5 - + - + - + - + D D R0 M0 D D RO MO + + + + + + + + D D A1 A2 D D A1 A2 0.5+ + + + + + + + ms D D A3 A4 D D A3 A4 + + + + + + + + D D E T D D E T - + + + + + + + + D D R1 M1 D D R1 M1 + + + + + + + + D D A1 A2 D D A1 A2 + + + + + + + + D D A3 A4 D D A3 A4 4 ms + + + + + + + + D D E T D D E T + + + + + + + + = = + + + + + + + + D D R7 M7 D D R7 M7 + + + + + + + + D D A1 A2 D D A1 A2 + + + + + + + + D D A3 A4 D D A3 A4 + + + + + + + + D D E T D D E T - + - + D1 CV1 D2 CV2 + + + - + Basic access 1 Basic access 2 FIGURE 5Q.512 A1..A4:Activationdeactivation, test loop and line feed control T:Transparent channel E:Indication of information in the M-channel M: Monitor channel Rbit multiframe alignment word for every basic access: 1 0 1 0 0 1 0 1 ---4 ms------ Coding of the Abits The Abits are used for the coding of the Functional Elements across the V1 reference point, as identified in Recommendation I.AA. The coding for the Abits is given in Tables 2Q.512 and 3Q.512. TABLE 2Q.512 + + Bits Command Corresponding to the functional A1 A2 A3 A4 Exchange - BAMX elements identified in I.AA + - + - + 0 0 0 0 Idle Power down state 0 0 0 1 Not used - 0 0 1 0 National use - 0 0 1 1 Not used - 0 1 0 0 Req. REG loop FE 6 0 1 0 1 Req. NT loop FE 4 0 1 1 0 Req. LT loop FE 5 0 1 1 1 (M)PH-AR FE 1 1 0 0 0 MPH-LSARDR T FE 3 1 0 0 1 National use - 1 0 1 0 National use - 1 0 1 1 Not used - 1 1 0 0 Disable Req. Switch off power +U transmit sig. 1 1 0 1 Not used - 1 1 1 0 Not used - 1 1 1 1 (M)PH-DR FE 2 + + TABLE 3Q.512 + + Bits Indications Corresponding to the functional A1 A2 A3 A4 Exchange - BAMX elements identified in I.AA + - + - + 0 0 0 0 MPH-DI FE 12 0 0 0 1 Not used - 0 0 1 0 Not used - 0 0 1 1 PH-AI FE 7 0 1 0 0 Not used - 0 1 0 1 National use - 0 1 1 0 Not used - 0 1 1 1 Start timer T1 FE X 1 0 0 0 MPH-LSAI FE 8 1 0 0 1 Not used - 1 0 1 0 MPH-EI FE 18 1 0 1 1 Sync loss U Synchronization loss on U interf. 1 1 0 0 Disable ind. PowerTransmitterWake up disabl. 1 1 0 1 Not used - 1 1 1 0 National use - 1 1 1 1 MPH-EI General fault condition BAMX + + Mbit coding The Mbit coding is specified in Tables 4Q.512 and 5Q.512. TABLE 4Q.512 + + M0 M1 M2 M3 M4 M5 M6 M7 Exchange - BAMX description + 0 0 0 0 0 0 0 0 Idle state 0 0 0 0 0 0 0 1 National use 0 0 0 0 0 0 1 0- + + Reserved for future applications 0 0 0 0 0 1 1 1- + 0 0 0 0 1 0 0 0- Reserved for error counter readout 1 1 1 0 1 1 0 1- + + Reserved for future applications 1 1 1 0 1 1 1 0- + 1 1 1 0 1 1 1 1 National use 1 1 1 1 0 0 0 0- + + National use 1 1 1 1 1 1 1 0- + 1 1 1 1 1 1 1 1 Idle state + + TABLE 5Q.512 + + M-bit responses BAMX - Exchange description + Values of monitor counters: Eq. BER 1 octet, binary coded 1 octet binary coded + + Ebit coding The Ebit coding is given in Table 6Q.512. TABLE 6Q.512 + + E Description + - + 0 Valid data in the following M-bit 1 No valid data in the following M-bit + +